Abstract
Brz (brassinazole) was synthesized as the first specific inhibitor for brassinosteroid biosynthesis by Asami et al. Target of Brz220 is the cytochrome P450 enzyme encoded by DWF4. In the light, plants treated with Brz display dwarfism with the dark-green leaves. Brassinosteroid deficiency in the dark with Brz caused the deetiolation. In order to clarify in detail the mechanisms of brassinosteroid signal transduction, we had already identified brassinosteroid biosynthesis inhibitor Brz insensitive mutant bil1 from EMS-mutation lines, and bil5 from fast neutron-mutation lines. We tried to screen new bil mutants from Arabidopsis activation-tag lines. Screened mutants showed long hypocotyl with Brz in the dark, slender dwarf phenotype that related to excessive epinastic leaves, and thin inflorescence. In the later growth stage, the mutants showed short but increased number of inflorescence. Genetic analysis of these mutants is in progress.
